我是Android谷歌地图的新手。我在一些教程之后在地图上写了一些代码，但是我看不到输出。我生成并使用了map-key APIv2。请帮我解释一下代码。
的Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.examp.nowmap"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<permission
android:name="com.examp.nowmap.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<uses-permission android:name="com.examp.nowmap.package.permission.MAPS_RECEIVE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.examp.nowmap.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyBbMfnc3rVf89ie564M8VgKZpfpbLHKyKo" />
</application>
</manifest>
MainActivity.java
package com.examp.nowmap;
@SuppressLint("NewApi")
public class MainActivity extends Fragment {
private Location currentLocation = null;
private LocationManager locationManager;
private GeoPoint currentPoint;
TextView location1;
ArrayList<LatLng> markerPoints;
GoogleMap map;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getLastLocation();
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.main, container, false);
// ...some other stuff being done here...
// Return view
return view;
}
public void getLastLocation(){
String provider = getBestProvider();
currentLocation = locationManager.getLastKnownLocation(provider);
this.markerPoints = new ArrayList<LatLng>();
LatLng fromPosition = new LatLng(currentLocation.getLatitude(), currentLocation.getLongitude());
LatLng toPosition = new LatLng(29.633289, -82.305838);
LatLng toPosition1 = new LatLng(40.044438,-106.197281);
MainActivity.this.markerPoints.add(fromPosition);
MainActivity.this.markerPoints.add(toPosition);
// Getting URL to the Google Directions API
String url = MainActivity.this.getDirectionsUrl(fromPosition, toPosition);
DownloadTask downloadTask = new DownloadTask();
// Start downloading json data from Google Directions API
downloadTask.execute(url);
if(currentLocation != null) {
setCurrentLocation(currentLocation);
} else {
// do something
}
}
public String getBestProvider() {
locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setPowerRequirement(Criteria.NO_REQUIREMENT);
criteria.setAccuracy(Criteria.NO_REQUIREMENT);
String bestProvider = locationManager.getBestProvider(criteria, true);
return bestProvider;
}
public void setCurrentLocation(Location location){
// Get current location
int currLatitude = (int) (location.getLatitude()*1E6);
int currLongitude = (int) (location.getLongitude()*1E6);
currentPoint = new GeoPoint(currLatitude,currLongitude);
// Set current location
currentLocation = new Location("");
currentLocation.setLatitude(currentPoint.getLatitudeE6() / 1e6);
currentLocation.setLongitude(currentPoint.getLongitudeE6() / 1e6);
}
private String getDirectionsUrl(LatLng origin, LatLng dest) {
// Origin of route
String str_origin = "origin=" + origin.latitude + "," + origin.longitude;
// Destination of route
String str_dest = "destination=" + dest.latitude + "," + dest.longitude;
// Sensor enabled
String sensor = "sensor=false";
// Building the parameters to the web service
String parameters = str_origin + "&" + str_dest + "&" + sensor;
// Output format
String output = "json";
// Building the url to the web service
String url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + parameters;
return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException {
String data = "";
InputStream iStream = null;
HttpURLConnection urlConnection = null;
try
{
URL url = new URL(strUrl);
// Creating an http connection to communicate with url
urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(iStream));
StringBuffer sb = new StringBuffer();
String line = "";
while ((line = br.readLine()) != null) {
sb.append(line);
}
data = sb.toString();
br.close();
} catch (Exception e) {
Log.d("Exception while downloading url", e.toString());
} finally {
iStream.close();
urlConnection.disconnect();
}
return data;
}
// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, ArrayList<String>> {
@Override
protected ArrayList<String> doInBackground(String... urlList) {
try {
ArrayList<String> returnList = new ArrayList<String>();
for (String url : urlList) {
// Fetching the data from web service
String data = MainActivity.this.downloadUrl(url);
returnList.add(data);
}
return returnList;
} catch (Exception e) {
Log.d("Background Task", e.toString());
return null; // Failed, return null
}
}
// Executes in UI thread, after the execution of
// doInBackground()
@Override
protected void onPostExecute(ArrayList<String> results) {
super.onPostExecute(results);
ParserTask parserTask = new ParserTask();
for (String url : results) {
parserTask.execute(url);
}
// Invokes the thread for parsing the JSON data
// parserTask.execute(results);
}
}
/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, ArrayList<List<HashMap<String, String>>>> {
// Parsing the data in non-ui thread
@Override
protected ArrayList<List<HashMap<String, String>>> doInBackground(String... jsonData) {
try {
ArrayList<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String, String>>>();
// for (String url : jsonData) {
for (int i = 0; i < jsonData.length; i++) {
JSONObject jObject = new JSONObject(jsonData[i]);
DirectionsJSONParser parser = new DirectionsJSONParser();
// Starts parsing data
routes = (ArrayList<List<HashMap<String, String>>>) parser.parse(jObject);
}
return routes;
} catch (Exception e) {
Log.d("Background task", e.toString());
return null; // Failed, return null
}
}
// Executes in UI thread, after the parsing process
@Override
protected void onPostExecute(List<List<HashMap<String, String>>> result)
{
if (result.size() < 1)
{
Toast.makeText(getActivity(), "No Points", Toast.LENGTH_SHORT).show();
return;
}
TextView tv1 = (TextView) getActivity().findViewById(R.id.location1);
TextView tv2 = (TextView) getActivity().findViewById(R.id.location2);
TextView tv3 = (TextView) getActivity().findViewById(R.id.location3);
TextView tv4 = (TextView) getActivity().findViewById(R.id.location4);
TextView[] views = {tv1, tv2, tv3, tv4};
// Traversing through all the routes
for (int i = 0; i < result.size(); i++)
{
// Fetching i-th route
List<HashMap<String, String>> path = result.get(i);
String distance = "No distance";
// Fetching all the points in i-th route
for (int j = 0; j < path.size(); j++)
{
HashMap<String, String> point = path.get(j);
if (j == 0)
{
distance = point.get("distance");
continue;
}
}
// Set text
views[i].setText(distance);
}
}
}
}
main.xml中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<fragment
android:name="com.google.android.gms.maps.SupportMapFragment"
xmlns:map="http://schemas.android.com/apk/res-auto"
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
答案 0 :(得分：0)
这是谷歌地图的一个常见问题，很多人都会问这个并且研究显示出如此多的主观问题......试试这个：
检查您是否在Google API控制台上启用了Google Maps Android API v2 服务。如果您没有，则启用它，然后按生成新密钥 重新创建 API密钥。
双重和三重检查所有必需的权限以及您复制和粘贴的API密钥。
在您的设备或AVD上卸载该应用并重新安装并尝试...有时需要完全刷新。
使用LatLng
转到特定位置这是一个易于使用的方法，我设计去特定的位置。把它放在你的Activity里面或者创建一个新的Class并简单地将数据传递给它：）
/** goToLocation
* @param map - You GoogleMap reference
* @param location - your LatLng value
* @param zoom Float - ie. 15
* @param b Boolean - Animate camera movement: true or false
*/
public void goToLocation(GoogleMap map, LatLng ll, float zoom, boolean b) {
if (b == true) {
map.animateCamera(CameraUpdateFactory.newLatLngZoom(ll, zoom));
} else {
map.moveCamera(CameraUpdateFactory.newLatLngZoom(ll, zoom));
}
}
答案 1 :(得分：0)
在你的清单中你提到了这一点。 uses-library android：name =“com.google.android.maps”删除它。这是旧版本，即谷歌地图v1
并检查您的密钥是否使用调试密钥或释放密钥。
发布密钥程序在这里
Google Map Android API v2 can't display map in play store application
答案 2 :(得分：0)
请参阅我针对特定位置问题的编辑回答。